Because he was losing the fight badly and started panicking. That's why. The flashbangs and darkness didn't help him, and pretty soon the fight was over.

Even if he wanted to use other methods, he didn't have the time or chance to do so.

__________________Supermanwith Batman - Whatever It Is... - Countdown until midnight release on March 25, 2016 - updated!
A hero can be anyone. Even a man doing something as simple and reassuring as putting a coataround a young boy's shoulders to let him know the world hadn't ended.